Mechanical keyboard is a common kind of keyboard with a separate switch for each key to control its on/off. Mechanical keyboard has always been a representative of high-end products, and it is welcomed by more and more computer users and gamers. Normally the switch used is a metal-contact mechanical key switch. The switch is installed in the housing, which controls the on/off of the switch through contact between the metal contact of the static pressure plate and the dynamic pressure plate. During the displacement of the handle of the mechanical switch, the metal contact of the dynamic pressure plate and that of the static pressure plate contact with each other so that the mechanical switch is on. When the handle of the mechanical switch is released, the dynamic pressure plate returns to the original position under the elastic force of the spring, and the metal contact of the dynamic pressure plate separates with the metal contact of the static pressure plate so that the mechanical switch is off. With this kind of scheme, the metal contact of the mechanical switch is easily damaged because in the process of pressing the key, the elasticity of the dynamic pressure plate becomes greatly different from the original state with increasing number of use, resulting in insensitive contact or unavailable connection of the metal contact, limited service life and causing trouble to the user. In addition, the traditional optical axis mechanical keyboard arranges the crystal light transmitting component and light receiver in the key switch with the bottom pin soldered on PCB and the key switch engaged in the slot; finally the PCB and the iron plate are fixed by a fixing column on the rotatable iron plate. Once a key is damaged, it is troublesome to disassemble and repair it. It is necessary to not only unscrew the fixing column, but also pull the crystal light receiver and light transmitting component from the PCB. Under the circumstance, it is difficult to handle and is easy to cause damage to the keyboard. Moreover, this kind of keyboard is also disadvantageous for large-scale industrial production.